Composite panel

ABSTRACT

A composite wall panel for use in vehicles having a floor structure and a front wall, the composite wall panel including a first polymer resin layer having a plurality of unidirectional fibers embedded therein that are substantially parallel to a first axis, and a second polymer resin layer having a plurality of unidirectional fibers embedded therein that are substantially parallel to a second axis, the second polymer resin layer being bonded to the first polymer resin layer so that the second axis is substantially perpendicular to the first axis. The composite wall panel is disposed so that the first axis is substantially parallel to the floor structure, and the rigidity of the composite wall panel is greater along the first axis than the second axis.

FIELD OF THE INVENTION

The present invention relates generally to a composite panel having agreater degree of rigidity along a first axis than along a second axisthat is perpendicular to the first axis.

BACKGROUND OF THE INVENTION

It is known to use wall panels having a thin outer sheet of fiberglasswhen constructing walls of various vehicles such as recreationalvehicles, trailers, mobile homes, etc., because the thin fiberglasssheet presents an aesthetically pleasing surface. For example, one suchwall panel consists of the fiberglass sheet adhered to a plywoodsubstrate, such as by gluing. However, plywood substrates aresusceptible to water damage, surface inconsistencies such as knots,irregular grain, etc., and joints between the plywood substrates ofadjacent panels can be difficult to construct smoothly. As well, otherknown wall panels may have outer surfaces formed by other materials suchas, but not limited to, polymer films, aluminum, etc.

Another known wall panel includes a fiberglass film adhered to afiberglass/polypropylene substrate layer. These wall panels work wellfor planar wall sections, but tend to be fairly rigid. Difficulties canarise when using such wall sections in the front portions of trailers,recreational vehicles, etc., where it is often desirable to curve thewall, for example, where the top of a wall section joins an opposingroof panel. Attempts have been made to add more flexible top sections tosuch wall panels, which lead to additional manufacturing complexity,joints in the panels and subsequent cost increases. For example, topwall panel sections formed from plywood with multiple, shallow elongatedgrooves therein have been utilized to allow greater flexibility, as wellas top sections including multiple elongated plywood strips adhered to aflexible base layer.

The present invention recognizes and addresses considerations of priorart constructions and methods.

SUMMARY OF THE INVENTION

One embodiment of the present disclosure provides a composite wall panelfor use in vehicle or trailer having a floor structure that is supportedby at least one pair of wheels, a roof structure spaced from anddisposed opposite the floor structure, a pair of opposed sidewallsspaced from each other and extending between the floor structure and theroof structure, and a front wall and a rear wall opposing each other andextending between the floor structure and the roof structure, thecomposite wall panel including a first polymer resin layer having aplurality of unidirectional fibers embedded therein, the plurality ofunidirectional fibers being substantially parallel to a first fiber axisof the composite wall panel, a second polymer resin layer having aplurality of unidirectional fibers embedded therein, the plurality ofunidirectional fibers being substantially parallel to a second fiberaxis of the composite wall panel. The second polymer resin layer isbonded to the first polymer resin layer so that the second fiber axis issubstantially perpendicular to the first fiber axis. A third polymerresin layer includes a plurality of unidirectional fibers embeddedtherein, the third polymer resin layer being bonded to the secondpolymer resin layer opposite the first polymer resin layer so that theplurality of unidirectional fibers of the third polymer layer issubstantially perpendicular to the first fiber axis of the compositewall panel. The composite wall panel forms a curved portion of the frontwall and is disposed so that the first fiber axis is substantiallyparallel to the floor structure, and the rigidity of the composite wallpanel is greater along the first fiber axis than the second fiber axis.

Another embodiment of the present disclosure provides a vehicle having achassis including a wheel assembly, and a body supported by the chassis,the body including a floor structure, a roof panel, a pair of sidewalls,a rear wall and a front wall. The front wall includes a curved portion,the curved portion being formed by at least one composite wall panel.The composite wall panel includes a first polymer resin layer having aplurality of unidirectional fibers embedded therein, the plurality ofunidirectional fibers being substantially parallel to a first fiber axisof the composite wall panel, a second polymer resin layer having aplurality of unidirectional fibers embedded therein, the plurality ofunidirectional fibers being substantially parallel to a second fiberaxis of the composite wall panel. The second polymer resin layer isbonded to the first polymer resin layer so that the second fiber axis issubstantially perpendicular to the first fiber axis. A third polymerresin layer includes a plurality of unidirectional fibers embeddedtherein, the third polymer resin layer being bonded to the secondpolymer resin layer opposite the first polymer resin layer so that theplurality of unidirectional fibers of the third polymer layer issubstantially perpendicular to the first fiber axis of the compositewall panel. The composite wall panel forms a curved portion of the frontwall and is disposed so that the first fiber axis is substantiallyparallel to the floor structure, and the rigidity of the composite wallpanel is greater along the first fiber axis than the second fiber axis.

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate one or more embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendeddrawings, in which:

FIG. 1 is a perspective view of a vehicle including a composite panel inaccordance with the present disclosure;

FIG. 2 is a partial cross-sectional view of the composite panel of thevehicle as shown in FIG. 1; and

FIG. 3 is a schematic illustration of an apparatus for forming acomposite panel in accordance with the present disclosure.

Repeat use of reference characters in the present specification anddrawings is intended to represent same or analogous features or elementsof the invention according to the disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to presently preferred embodimentsof the invention, one or more examples of which are illustrated in theaccompanying drawings. Each example is provided by way of explanation,not limitation, of the invention. In fact, it will be apparent to thoseskilled in the art that modifications and variations can be made in thepresent invention without departing from the scope and spirit thereof.For instance, features illustrated or described as part of oneembodiment may be used on another embodiment to yield a still furtherembodiment. Thus, it is intended that the present invention covers suchmodifications and variations as come within the scope of the appendedclaims and their equivalents.

Referring now to the Figures, FIG. 1 shows a recreational vehicle,specifically a trailer 10, in which composite wall panels (FIGS. 2 and3) constructed in accordance with an embodiment of the presentdisclosure are used. As shown, trailer 10 includes a body 12 that issupported by a chassis 24. Body 12 includes a floor structure 14 that issecured to chassis 24, a roof panel 22, a pair of parallel, opposingside walls 16 (only one of which is shown in FIG. 1), a front wall 18and a rear wall 20, all extending between floor structure 14 and roofpanel 22. As in the example shown, it is known for the vehicle frontwall to include at least a curved portion to both improve the vehicle'saerodynamics and provide an aesthetically pleasing appearance. In theinstant case, the front wall 18 of trailer 10 forms a continuous curve(when considered in a plane perpendicular to the generally planar floorand including a longitudinal center axis of the floor perpendicular tothe wheel axis) between floor structure 14 and roof panel 22. To allowtowing by another vehicle, chassis 24 includes a hitch receiver 28 andwheel assembly 26.

FIG. 2 provides a cross-sectional view of a composite wall panel 100 inaccordance with one embodiment of the present disclosure. Composite wallpanel 100 includes multiple fiber reinforced polymer layers. Each of afirst polymer resin layer 102, a second polymer resin layer 104, and athird polymer resin layer 106 includes a plurality of unidirectionalfibers embedded in a co-polymer material. For the embodiment shown, theunidirectional fibers are continuous strand glass fibers that areembedded in a polypropylene co-polymer so that the continuous strandglass fibers within each layer are generally parallel to each other. Thefirst, second and third polymer resin layers 102, 104 and 106 arepositioned over one another and are consolidated to form a unitarypolymer resin layer 103 of composite wall panel 100. Second polymerresin layer 104 is disposed between first polymer resin layer 102 andthird polymer resin layer 106 such that unidirectional fibers 107 ofsecond polymer resin layer 104 are aligned in a direction that isperpendicular to a direction in which unidirectional fibers 107 of firstpolymer resin layer 102 and third polymer resin layer 106 are aligned.Specifically, unidirectional fibers 107 of first polymer resin layer 102and third polymer resin layer 106 are aligned substantially parallel toa first fiber axis 120 (FIG. 1) of composite wall panel 100, whereasunidirectional fibers 107 of second polymer resin layer 104 are alignedsubstantially parallel to a second fiber axis 122 of composite wallpanel 100.

In the embodiment shown in FIG. 2, the first, second and third polymerresin layers are similar, meaning both the thickness of the layers andthe density of unidirectional fibers within each layer are substantiallythe same. In the present embodiment, the first, second and third polymerlayers are preferably between about 0.008″ to about 0.016″ thick andhave a weight of about 0.06 to about 0.15 lbs/sq. ft. As such, the glassto resin ratio of unidirectional fibers 107 within unitary polymer resinlayer 103 of composite wall panel 100 that are substantially parallel tofirst fiber axis 120 is greater than the glass to resin ratio ofunidirectional fibers 107 within unitary polymer resin layer 103 thatare substantially parallel to second fiber axis 122. That is, a greaternumber of unidirectional fibers within unitary layer 103 (i.e. thecombined layers 102/104/106) are aligned parallel to the first fiberaxis direction (120) as compared to the number of unidirectional fibersaligned parallel to the second fiber axis direction (122), and there isa greater cross sectional (in a plane including axis 122 andperpendicular to axis 120) area of unidirectional fibers in direction120 than the cross sectional (in a plane including axis 120 andperpendicular to axis 122) area of unidirectional fibers in direction122. Composite wall panel 100 therefore exhibits greater rigidity, andcorrespondingly resistance to bending, along first fiber axis 120 thanalong second fiber axis 122.

Composite wall panel 100 exhibits greater rigidity along first fiberaxis 120 based not only on the higher cross-sectional area ofunidirectional fibers aligned with first fiber axis 120, but also due tothe position of those unidirectional fibers relative to a center plane101 of unitary polymer resin layer 103 of the composite wall panel.Specifically, center plane 101 is disposed in the middle of unitarypolymer resin layer 103, substantially parallel to the outermost majorsurfaces 103 a and 103 b of the layer. As such, center plane 101 isdisposed within second polymer resin layer 104. Therefore, as shown inFIG. 2, unidirectional fibers 107 of first and third polymer resinlayers 102 and 106 are spaced at greater distances (considered in adirection perpendicular to center plane 101) from center plane 101 thanare unidirectional fibers 107 of second polymer resin layer 104. Whenattempting to bend composite wall panel 100 along first fiber axis 120,unidirectional fibers 107 of first and second polymer resin layers 102and 106 are under greater compression and tension (depending on thebending direction) than are those of second polymer resin layer 104 whenattempting to bend composite wall panel 100 relative to second fiberaxis 122. In short, because unidirectional fibers 107 of second polymerresin layer 104 are closer to center plane 101, they are placed underless compression and/or tension during bending. Even if the thickness ofsecond polymer resin layer 104 is equal to that of combined first andthird polymer resin layers 102 and 106 (which is an embodiment under thepresent disclosure, as are thicknesses of layer 104 between half of andequal to the combined thickness of layers 102 and 106), the compositewall panel exhibits greater rigidity along first fiber axis 120 due tothe increased distance of unidirectional fibers 107, of the first andthird polymer resin layers, from center plane 101.

In other embodiments, the glass-to-resin ratios of unidirectional fibers107 in layers 102/106 and of unidirectional fibers 107 in layer 104(each consider within layer 103 as a whole) may vary, as may therelative thicknesses of those two layers (102/106 and 104). In certainembodiments, for example, unidirectional fibers 107 within center layer104 of unitary polymer resin layer 103 of composite wall panel 100 arewithin (whether considered by weight, number of fibers of constantconstruction, or by layer thicknesses when fiber density remainsconstant) a range of about 20% to about 40% of the total fibers inunitary layer 103, whereas unidirectional fibers 107 within outer layers102 and 106 of layer 103 are within a range of about 60% to about 80% ofthe total fibers in layer 103. That is, in these embodiments, about 20%to about 40% of the fibers in layer 103 are aligned in direction 122,while about 60% to about 80% of the fibers in layer 103 are aligned indirection 120. In these or other embodiments, the overall thickness ofcomposite wall panel 100 is within a range of about 0.020″ to about0.070″, with a weight percent glass of about 30% to about 75%.

As further shown in FIG. 2, composite wall panel 100 also includes afirst scrim layer 108 and a second scrim layer 110 that are laminated tothe outermost surfaces of first polymer resin layer 102 and thirdpolymer resin layer 106, respectively. First and second scrim layers 108and 110 provide a relatively rough surface to which additional layersmay be readily adhered. For example, in the present embodiment, athermoset fiberglass sheet 112 is adhered to first scrim layer 108 withadhesive bonding to provide an aesthetically pleasing outer surface ofcomposite wall panel 100. In one or more embodiments, fiberglass sheet112 has a thickness of about 0.010″ to about 0.060″. Alternately, theouter layer of composite wall panel 100 may be formed by a fiberglassreinforced thermoset resin including a gel coat.

In use, referring again to FIG. 1, composite wall panel 100 may be usedto form any one, or all, of side walls 16, front wall 18, rear wall 20and roof panel 22. However, the advantages offered by composite wallpanel 100, those being increased rigidity along first fiber axis 120with respect to second fiber axis 122, are most notable when compositewall panel 100 is used to form a wall including a curved portion, suchas front wall 18. As shown, by aligning composite wall panel 100 suchthat its first fiber axis 120 is substantially parallel to thehorizontal floor structure 14 of trailer 10, rigidity of front wall 18can be maintained along first fiber axis 120, while still allowing forflexibility along second fiber axis 122 so that front wall 18 may begiven the desired amount of curve. Further, composite wall panel 100 maybe used to form roof panel 22, wherein composite wall panel 100 isaligned such that its first fiber axis 120 is substantially parallel tothe longitudinal center axis of the trailer's floor. In this manner, therigidity of roof panel 22 is maintained from front to back of the panel,while still allowing for the side edges of the roof panel to be bentdownwardly to meet the to portions of sidewalls 16. As such, roof panel22 can be unitarily formed.

FIG. 3 schematically illustrates a machine 200 that consolidates themultiple layers of material into the composite wall panel shown in FIG.2. That is, machine 200 applies heat and pressure to the multiple layersto consolidate the raw materials into a substantially rigid sheet and toachieve a desired density in the laminate. One suitable consolidationmachine 200 is a contact heat oven manufactured and sold by Schott &Meissner GmbH of Germany under the name THERMOFIX. FIG. 3 should beunderstood to be a representative schematic example provided forillustrative purposes, however, and other consolidation machines may beused to form the laminate of the present invention.

A rack 202 of machine 200 holds multiple rolls of material that are fedinto a pair of guide rollers 204 driven by a lower belt 206 so that thelayers are carried down stream into the machine on the lower belt. Eachlayer is coplanar with the adjacent upper and/or lower layers and isgenerally of the same length and width so that the resultant materialhas uniform properties throughout.

The raw materials that form the composite panel are stored on largerolls in rack 202. FIG. 3 illustrates seven materials being fed in acoplanar manner into consolidator 200: a first scrim layer 108, a firstoptional adhesive layer 222, a first polymer resin layer 102, a secondpolymer resin layer 104, a third polymer resin layer 106, a secondoptional adhesive layer 222 and a second scrim layer 110. Each layer isapproximately the same width and length as the other layers so that theresultant composite laminate panel 100 is uniform from end to end. Inthe previously described embodiment of composite wall panel 100 (FIG.2), adhesive layers 222 are not used because first and second scrimlayers 108 and 110 are embedded in the outer surfaces of first polymerresin layer 102 and third polymer resin layer 106, respectively, duringthe lamination process. However, in alternate embodiments, adhesivelayers 222 may be used. Suitable adhesive layers include a UAFpolyurethane adhesive film and a PAF polyester based heat activatedadhesive film, each manufactured by Adhesive Films, Inc. of Pine Brook,N.J. It should also be understood that other forms of adhesives can beused. For example, spray adhesive can be applied to the outer surfacesof first and third polymer resin layers 102 and 106 prior to being fedinto guide rollers 204. In another example, the first and third polymerresin layers can be roll coated with adhesive prior to being fed intoguide rollers 204.

Referring again to FIG. 3, belt 206 faces opposite a belt 208 so thatthe layers of material are sandwiched between the belts. Belts 206 and208 are coated with a non-adherent releasing film surface, for examplestainless steel, TEFLON or other suitable material, so that the laminatematerial easily releases from the belt at the end of the machine. Belts206 and 208 pass the layers through a heating stage 210, a calendarstage 212 and a cooling stage 214. Heating stage 210 includes pan typeheating elements 216 that carry heated oil to conduct heat through belts206 and 208 and into the input materials. The heating of first, secondand third polymer resin layers 102, 104 and 106, respectively, and firstand second scrim layers 108 and 100 causes the thermoplastic materialsto flow so that added pressure by belt rollers 218 in calendar section212 causes scrim layers 108 and 110 to embed or mechanically bond withthe outer surfaces of unitary polymer resin layer 103 (FIG. 2). The heatalso causes adhesive films 222, if present, to melt or activate.

Belt rollers 218 of calendar stage 212 apply sufficient pressure to thematerials so that they bond to form a generally uniform composite panel100. The amount of pressure depends on the temperature of the inputmaterials and the desired thickness of composite panel 100. Once thematerials have been consolidated, the soft pliable composite panel 100solidifies at cooling stage 214. The cooling stage employs cooling pans220 that carry water to dissipate heat retained in the laminate. Thetemperature of the cooling water varies between 10 and 20 degreescentigrade depending on the number of layers in the laminate and thespeed of the machine so that in a preferred embodiment, the laminate iscooled to a temperature at which the laminate panel is stable and willnot warp. Consolidating machine 200 is able to form a continuous sheetof varying width and length of composite material that can then berolled, or cut and stacked in sheets, for storage.

While one or more preferred embodiments of the invention are describedabove, it should be appreciated by those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the scope and spirit thereof. For example,alternate embodiments of composite wall panels in accordance with thepresent disclosure may have fewer, or more, layers than the number ofthe discussed embodiments. It is intended that the present inventioncover such modifications and variations as come within the scope andspirit of the appended claims and their equivalents.

What is claimed is:
 1. A composite wall panel of a vehicle having afloor structure that is supported by at least one pair of wheels, a roofstructure spaced from and disposed opposite the floor structure, a pairof opposed sidewalls spaced from each other and extending between thefloor structure and the roof structure, and a front wall and a rear wallopposing each other and extending between the floor structure and theroof structure, the composite wall comprising: a first polymer resinlayer having a plurality of unidirectional fibers embedded therein, theplurality of unidirectional fibers being substantially parallel to afirst fiber axis of the composite wall panel; a second polymer resinlayer having a plurality of unidirectional fibers embedded therein, theplurality of unidirectional fibers of the second polymer resin layerbeing substantially parallel to a second fiber axis of the compositewall panel, the second polymer resin layer being bonded to the firstpolymer resin layer so that the second fiber axis is substantiallyperpendicular to the first fiber axis; and a third polymer resin layerhaving a plurality of unidirectional fibers embedded therein, the thirdpolymer resin layer being bonded to the second polymer resin layeropposite the first polymer resin layer so that the plurality ofunidirectional fibers of the third polymer layer is substantiallyparallel to the first fiber axis of the composite wall panel, the first,second and third polymer resin layers forming a unitary polymer resinlayer, wherein the composite wall panel forms a curved portion of thefront wall and is disposed so that the first fiber axis is substantiallyparallel to the floor structure, and rigidity of the composite wallpanel is greater along the first fiber axis than the second fiber axis.2. The composite wall panel of claim 1, wherein a glass to resin ratioof the unidirectional fibers within the unitary polymer resin layer thatare parallel to the first fiber axis is greater than a glass to resinratio of the unidirectional fibers within the unitary polymer resinlayer that are parallel to the second fiber axis.
 3. The composite wallpanel of claim 2, wherein respective thicknesses of the first polymerresin layer, the second polymer resin layer, and the third polymer resinlayer in a direction perpendicular to the first fiber axis and thesecond fiber axis are substantially the same.
 4. The composite wallpanel of claim 3, further comprising: a first scrim layer bonded to anouter surface of the first polymer resin layer; and a second scrim layerbonded to an outer surface of the third polymer resin layer.
 5. Thecomposite wall panel of claim 4, further comprising a fiberglass sheetbonded to one of the first and the second scrim layers.
 6. The compositewall panel of claim 1, wherein thickness of the second polymer resinlayer in a direction perpendicular to the first fiber axis and thesecond fiber axis is greater than thickness of the first polymer resinlayer in the direction and thickness of the third polymer resin layer inthe direction.
 7. The composite wall panel of claim 1, wherein theunidirectional fibers of the first, the second, and the third polymerresin layers are glass fibers.
 8. A vehicle comprising: a chassisincluding a wheel assembly; and a body supported by the chassis, thebody including a floor structure, a roof panel, a pair of sidewalls, arear wall and a front wall, the front wall including a curved portion,the curved portion being formed by at least one composite wall panel,the at least one composite wall panel comprising a first polymer resinlayer having a plurality of unidirectional fibers embedded therein, theplurality of unidirectional fibers being substantially parallel to afirst fiber axis of the at least one composite wall panel, a secondpolymer resin layer having a plurality of unidirectional fibers embeddedtherein, the plurality of unidirectional fibers of the second polymerresin layer being substantially parallel to a second fiber axis of theat least one composite wall panel, the second polymer resin layer beingbonded to the first polymer resin layer so that the second fiber axis issubstantially perpendicular to the first fiber axis, and a third polymerresin layer having a plurality of unidirectional fibers embeddedtherein, the third polymer resin layer being bonded to the secondpolymer resin layer opposite the first polymer resin layer so that theplurality of unidirectional fibers of the third polymer layer issubstantially parallel to the first fiber axis of the at least onecomposite wall panel, the first, second and third polymer resin layersforming a unitary polymer resin layer, wherein the at least onecomposite wall panel is disposed so that the first fiber axis issubstantially parallel to the floor structure, and rigidity of the atleast one composite wall panel is greater along the first fiber axisthan the second axis.
 9. The vehicle of claim 8, wherein a glass toresin ratio of unidirectional fibers within the unitary polymer resinlayer that are parallel to the first fiber axis is greater than a glassto resin ratio of the unidirectional fibers within the unitary polymerresin layer that are parallel to the second fiber axis.
 10. The vehicleof claim 8, further comprising: a first scrim layer bonded to an outersurface of the first polymer resin layer; and a second scrim layerbonded to an outer surface of the third polymer resin later.
 11. Thevehicle of claim 10, further comprising a fiberglass sheet bonded to oneof the first and the second scrim layers.
 12. The vehicle of claim 8,wherein respective thickness of the first, the second and the thirdpolymer resin layers are substantially the same in a directionperpendicular to the first fiber axis and the second fiber axis.
 13. Thevehicle of claim 8, wherein thickness of the second polymer resin layerin a direction perpendicular to the first fiber axis and the secondfiber axis is greater than thickness of the first polymer resin layer inthe direction and thickness of the third polymer resin layer in thedirection.